The invention relates to devices for supporting and presenting a plurality of workpieces to the machining or cutting element of a automatic machining device.
Recently, numerically controlled machining devices have become widely used. These devices are able to perform pre-programmed machining and drilling operations on workpieces very precisely and at very high speeds. Various stable fixturing systems, tooling blocks, and angle plates have been utilized to support one or more workpieces while the numerically controlled machining tool is performing its pre-programmed operations on the workpieces. However, when the numerically controlled machining device has completed its operations on all workpieces presented to it by a workpiece-supporting fixture, operation must be halted while the machined workpieces are removed from the fixture and unmachined workpieces are then attached to the fixture, or while a pre-loaded fixture is being aligned with and attached to the machining device. Since numerically controlled machining equipment is exceedingly expensive, it is very desirable to be able to keep it operating as close to one hundred percent of the time as possible. The time that the numerically controlled machining device remains idle while workpieces are being handled represents a loss in efficiency of use of the machine, and ultimately a loss in profitability of the workpieces or an increase in their cost.
Accordingly, it is an object of the invention to provide an improved workpiece-supporting apparatus that increases the number of workpieces that can be presented to the machining element of a numerically controlled machining tool by a single supporting device.
The previously known workpiece supporting blocks, such as ones manufactured by Mid-State Machine Products, Inc., of Winslow, Me., make four surfaces available for different workpiece setups. However, the different sides of the tooling blocks are used for different "backup jobs" which can be run if there is a problem with the control program or a delay in obtaining workpiece material for the present job. These tooling blocks do not increase the percentage of time that the numerically controlled machine device spindle is operating as much as would be desirable. Furthermore, it is inconvenient to maintain a sufficiently large supply of such tooling blocks to make it practical to efficiently pre-load a large number of workpieces.
Accordingly, it is another object of the invention to provide an improved apparatus and method for presenting workpieces to the spindle of a numerically controlled machining device during a higher percentage of the time than is accomplished by the closest known prior art tooling blocks.
It is another object of the invention to provide an improved method and apparatus to achieve efficient "pre-loading" of a large inventory of un-machined workpieces onto support elements for presenting the un-machined workpieces to the spindle of a numerically controlled machining device.
A variety of rotatable workpiece holders are shown in U.S. Pat. Nos. 3,336,828; 3,588,989; 3,830,485; 4,200,182 and 4,286,778.